Budi Purnama

Electrical characteristic of spin coated Fe-Porphyrin on Cu substrates

This paper describes the electrical-characteristics of Fe-Porphyrin thin films on Cu substrates. The thin layer samples used were deposited by spin coating methods on Cu-substrates at room temperature with and without induced magnetic field in the plane direction of the surface films. Fe-porphyrin was dissolved in chloroform and mixed with a magnetic stirrer for 60 min at a rotational speed of 200 rpm. The experimental results show that the mobility carrier charge of the Fe-Porphyrin layer with induced magnetic field during deposition has lower value than that without induced magnetic field case. The decrease of the mobility can be attribute to the change of the surface morphology in Fe-porphyrin films by means of increase in the nano-granular/nano-molecular size caused by the induce magnetic field.

Utilization of natural porphyrin thin films as a photosensitizer for photodetectors

In this study, photodetectors were assembled using natural porphyrin as a sensitizer, and their energy gap properties were investigated. The natural porphyrin thin film layered devices used in the experiments were deposited by spin coating on a patterned electrode of Cu printed circuit board substrates. The photo sensitive characteristics were measured both with and without illumination by white light. The photo sensitive effect increased with the number of layers. A maximum current of 2.6 nA was obtained when the films consisted of three layers and the current increased to 7.9 nA for seven layers. To clarify the results, the dependence of the number of layers on the energy gap was evaluated. The experiment results showed that the energy gap decreased linearly with increasing number of layers. The mutual combination of the photo sensitive effect and energy gap indicated that it is possible to apply natural porphyrin as a sensitizer for photodetector applications.

Concentration dependence of surface roughness in spin-coated Fe-porphyrin layer

The surface roughness of Fe–porphyrin thin layers was studied using atomic force microscopy. The thin layer samples used in these experiments were deposited by spin coating methods on indium–tin-oxide substrates under atmospheric conditions. The experimental results demonstrated that the Fe–porphyrin layers were observed as discrete nano-molecular islands. The surface roughness of the layer increased significantly with increasing concentration.

Preliminary Study of Bio-Impedance Based Sensor Using Organic Polymer Membrane for Identification of Pork and Beef

Bio-impedance based sensor using organic polymer-membrane was presented in this paper. The Ca-alginate with glycerol as plasticizer used in the experiments was fabricated by slip casting method on a glass substrates. After atmospheric heating treatment of edible films at 60°C for 24 hours, the films-membranes of 50 mm were obtained. Bio-impedance characterizations were carried out by LCR meter at room temperature. The experiment results showed that the sensor finely operated at low frequency i.e. less than 40 kHz. Response of the sensor increased with the increase of samples mass and became constant after a critical mass. Finally, bio-impedance responses of beef and pork were clearly indicated by a different magnitude that it is possible to apply the films-membranes as bio-sensor applications.